They have nicknames like Boomarang, Aya the Storm, Magzilla, Hurt Copain, and Susan B. Anarchy, but they’re not archvillains in a new comic book movie.

They’re junior high and high school students. And they play roller derby.

They train and occasionally host games in a converted taxicab graveyard on Belfield Avenue in Germantown that has no A/C in the summer and no heat in the winter. The place leaks when it rains. The flat track gets slick when it’s chilly, and grips when it’s warm.

But the littles, tweens, and teens who are part of the Philly Roller Derby Juniors program (ages 5 to 18) give up part of their weekends for the team, raise money for trips — last year’s destinations included South Carolina, Florida, and Colorado — and have created a second family for themselves.

The program was conceived in 2014 by members of the Liberty Belles adult roller derby team. Liberty Belles skater Faith Cortright (aka “Devoida Mercy”) had seen youth programs elsewhere in the country and decided to launch one at the Belles’ then-home base in Camden.

The adult Belles held a six-Saturday summer boot camp for younger players to gauge interest, and 26 girls showed up. When the actual program was launched, 23 of the girls returned and the Juniors were born. The inclusive group eventually took a vote to include boys because, said Cortright, “We live in a modern world with gender fluidity."

» READ MORE: This 9-year-old learned the Heimlich maneuver. The next day, she saved her best friend from choking.

Quickly, the team has grown into a powerhouse whose members hail from near and far. Three siblings come each week from Manhattan to play with the Juniors. Another group of All-Stars carpools down from North Jersey. A high school senior from Detroit made a commitment to play with Philly — she actually traveled here three out of every four weekends — before she aged out of Juniors at 18. The team has had five players in the Junior World Cup, and four skaters in the Junior Olympics.

In July, the Philly Junior All-Stars competed against the top 10 teams in the country and finished second in the coed division at the Junior Roller Derby Association Championships in Loveland, Colo. This was huge: Last year, the Juniors came in sixth place. The year before, they lost every game and finished 10th.

“Their performance in Loveland this year was the culmination of an entire season of hard work, on and off the track,” Cortright said, “and their desire to be a family unit was instrumental in their success. They have a love for each other that really contributes to their success. It’s magic.”

» READ MORE: Grading report cards: What’s in an A?

On Sunday, Sept. 8, the Juniors held their annual open house to try to grow the ranks and replace skaters who had headed off to college.

Under the watchful eyes and nurturing manner of Cortright and fellow coaches Beth Mast (aka Teflon Donna) and Laura Carnecchia (aka Bilt ta Spill, whose daughter is on the team), the newbies — wearing helmets and elbow and knee pads — took to the track with the Juniors, who helped open-house attendees learn the ropes. If the newcomers stick with it, they’ll learn to skate, fall, hit, and compete. But more importantly, they’ll learn about teamwork, strategy, friendship, and responsibility.

During a break in the action, Mast asked a gathering of new and veteran players what they liked about roller derby. Various Juniors shouted out:

“I like to go fast.”

“I like to hit people.”

“I like to see myself get better every practice.”

“We get opportunities to help each other grow.”

“We’re all weird.”

Not that weird. The weirdest part about the two-hour session was that none of the teens and tweens was on a cell phone. And if you think they’re all a bunch of tough punks looking to be part of sanctioned violence, you’d be wrong. Players come from performing arts schools, and from academically rigorous college-prep schools like Central and Masterman in Philly, and the Fieldston School in New York.

Said Cortright, “One official told me, ‘The energy of the kids is so good and positive. We love when we have your kids because we know it’s going to be a positive and respectful experience.’ That’s the best thing you can hear as a coach.”

Rory Bergan-Telep, 7, from West Philadelphia, attended the open house because, she said, “I have a lot of energy and I like skating.” She also seemed especially pleased with the idea of eventually hitting someone.

But there are rules in flat-track roller derby, which is not like the banked-track professional-wrestling type sport folks might remember from the 1970s — the kind with leg whips, flying elbows, and players being checked over the railing into the crowd.

First off, there is no railing — nor is the track banked or are the matches staged. Also, skaters are not allowed to trip or use their hands to push, or clock, an opponent with a pointy, but padded, elbow. Even negative cheering is a no-no: Parents have been booted from games for acting too much like ... parents.

Megan Rogers (aka Megalass), 18, who has just begun her freshman year at Stanford, attended the open house as an aged-out booster of the team and of her two younger siblings, who also play.

“Miraculously I’ve never gotten hurt from derby,” she said, even though she’s attracted to the game’s physicality. But she also loves the game’s newness.

“It’s growing crazy fast,” Rogers said. “Everything is evolving really quickly, so if you watch a game from even three years ago, it’s completely different than a game now.”

“People are always coming up with new strategies to figure out what’s most effective. I like that there’s no dogma for how you should play.”

No dogma, but a lot of junkyard dog. The Junior All-Stars and their B team, the Brawl-Stars, have a lot of competitive fight in them and take the game very seriously.

Rogers said that three months before the championships in Colorado, the team started training for the high altitude.

“A few people got altitude masks,” she said, “and it was really hard to breathe in them. The rest of us practiced with bandannas over our mouths.”

Julia Kubis (aka Julia Ghoulia), 14, a ninth-grader from the The Performing Arts Academy in Lakehurst, N.J., who’s interested in acting, said she’s attracted to the game’s strategy and she likes hitting people, which is frowned upon in acting class.

“It’s on skates and I’ve been skating forever,” she said. “I came to Philly last year and I fell in love with the team.”

Cortright credited the coaches, players, and supportive parents for that vibe. In fact, she said, “being involved with the juniors is the best part,” referring to the sport in which she has excelled. (On Sept. 15, she and the Liberty Belles finished third at the Women’s Flat Track Derby Association Playoffs in Seattle, allowing them to qualify for the World Championships in November in Montreal.)

“There’s a place for everybody,” she said, “and it’s great to see where they find their place.”